Coating · zinc
Hot-dip galvanized
A thick zinc coating made by dipping the parts in molten zinc. ISO 10684 requires a batch average of at least 50 µm on fasteners from M8 to M64 – thick enough that nuts are tapped oversize.
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What it is
How Hot-dip galvanized protects the joint.
01Molten zincParts are dipped in a zinc bath; the zinc bonds metallurgically with the steel.
02Thick and robustThe thickest of our zinc coatings, and resistant to handling damage.
03Thread allowanceBecause the layer is thick, nuts are tapped oversize (6AZ or 6AX) after galvanizing.
Applications
Where we use it.
01Structural steelBolted steel structures outdoors.
02Outdoor installationsFastenings exposed to weather where a thick zinc layer is wanted.
03Sets bolt + nutAlways ordered as a matching set, because of the oversize-tapped nuts.
Layer thickness
Thickness, fit and threads.
Layer thickness
≥ 50µm
ISO 10684: batch average at least 50 µm, local minimum 40 µm. Galvanizing is done at 455–480 °C or at 530–560 °C, never in between.
| Requirement (ISO 10684) | Value |
|---|---|
| Local thickness | ≥ 40 µm |
| Batch average | ≥ 50 µm |
| Nut thread | Tapped oversize 6AZ (mark Z) or 6AX (mark X) |
| Bath temperature | 455–480 °C or 530–560 °C |
How it is applied
From bare steel to coated part.
01Clean and pickleDegreasing and pickling to bare steel.
02FluxFluxing so the zinc wets the surface.
03Dip and spinDipping in molten zinc, then centrifuging to clear the threads.
04NutsNuts are tapped oversize after galvanizing and marked.
FAQ
Questions we get about Hot-dip galvanized.
- Can I use standard nuts?
- No. Nuts for hot-dip galvanized bolts are tapped oversize (6AZ or 6AX) and marked Z or X.
- Up to which property class?
- ISO 10684 covers bolts, screws and studs up to 10.9 and nuts up to class 12.
- Which sizes?
- Coarse-thread fasteners from M8 up to and including M64.
- HDG or Geomet?
- HDG is thicker and robust; zinc flake is thin and uniform, with an integral lubricant – better for fine threads.
Next step
Quote, compare or ask.
Reviewed October 2026 by HBS Solutions. Based on ISO 10684. Corrosion results always belong to a complete system (pretreatment, coating, thickness) – ask us for the data sheet of the system you order.
Other coatings
Compare with another coating.
TAKECOAT-1000Fluorocarbon polymer, 2 layersXylan 1070PTFE dry film, solvent-borneXylan 1424PTFE dry film, waterborneXylan 1427PTFE, extra corrosion protectionGeomet 500Zinc flake, integral lubricantZinc platedElectroplated zinc · ISO 4042SherardizedZinc diffusion · ISO 17668All coatingsCompare them side by side
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